Modern industrial gas turbines (IGT) as a rule are designed with annular combustors. In most cases, smaller IGTs are constructed with so-called “can-annular combustors”. In the case of an IGT with annular combustor, the combustion chamber is delimited by the side walls and also by the inlet and outlet planes of the hot gas. Such a gas turbine originates from FIGS. 1 and 2. The gas turbine 10 which is shown in detail in FIGS. 1 and 2 has a turbine casing 11 in which a rotor 12 which rotates around an axis 27 is housed. On the right-hand side, a compressor 17 for compressing combustion air and cooling air is formed on the rotor 12, and on the left-hand side a turbine 13 is arranged. The compressor 17 compresses air which flows into a plenum 14. In the plenum, an annular combustor 15 is arranged concentrically to the axis 27 and on the inlet side is closed off by means of a front plate 19 which is cooled with front-plate cooling air 20, and on the outlet side is in communication via a hot gas passage 25 with the inlet of the turbine 13.
Burners 16, which for example or preferably are designed as premix burners and inject a fuel-air mixture into the combustor 15, are arranged in a ring in the front plate 19. Such premix burners originate for example from EP-A1-321 809 or from EP-A1-704 657, wherein these publications and the development which is derived from them form an integrated constituent part of this application. The hot air flow 26 which is formed during the combustion of this fuel-air mixture reaches the turbine 13 through the hot gas passage 25 and is expanded in the turbine, performing work. The combustor 15 with the hot gas passage 25 is enclosed on the outside, with a space, by an outer and inner cooling shroud 21 or 31 which by means of fastening elements 24 are fastened on the combustor 15, 25 and between which and the combustor 15, 25 an outer and inner cooling passage 22 or 32 is formed. In the cooling passages 22, 32, cooling air, flows in the opposite direction to the hot gas flow 26 along the walls of the combustor 15, 25 into a combustor dome 18, and from there flows into the burners 16, or as front plate cooling air 20, flows directly into the combustor 15. The outer cooling shroud 21, as shown in FIG. 3, can be extended by means of an impingement cooling plate 30 which is provided with holes through which the cooling air jets enter the cooling passage 22 and impinge perpendicularly upon the outer shell 23.
The side walls of the combustor 15, 25 in this case are constructed either as shell elements or are formed as complete shells (outer shell 23, inner shell 33). When using complete shells, for installation reasons the necessity arises of providing a parting plane (34 in FIG. 4) which allows an upper half of the shell 23, 33 (23a in FIG. 4) to be detached from the remaining lower half of the shell (23b in FIG. 4), for example in order to install or to remove the gas-turbine rotor 12. The parting plane 34 correspondingly has two parting-plane welded seams which in the example of the gas turbine are located at the level of the machine axis 27 (FIG. 1).
A flange 28 with an encompassing groove 29 (FIG. 3) is attached at the ends of the shells 23, 33 and for reasons of mechanical strength can be reinforced by means of a connecting element in the form of a bridge 37 (FIG. 4) which reaches across the parting plane 34.
For the mechanical connection between the annular combustor 15, 25 and a subsequent turbine vane carrier TVC (pos. 47 in FIGS. 8 to 13), which carries the stator vanes of the subsequent turbine 13, and for dividing the plenum 14 into different chambers, sealing segment are provided, which are hooked on the combustor and on the turbine vane carrier in a movable manner and together form a sealing ring, which is arranged concentrically to the axis 27, between combustor and turbine vane carrier.
The sealing segments (similar to pos. 35′ in FIG. 4 and to pos. 35 in FIG. 5) should ideally feature the following functions or characteristics:                They seal two chambers of the plenum.        They should therefore also seal in relation to each other (requiring installation of a sealing lip between adjacent segments).        They mechanically interconnect two construction modules (combustor vs. turbine vane carrier).        They form an intermediate piece/transition piece between two construction modules (combustor vs. turbine vane carrier).        They are axially-symmetrically constructed (with exception of the segments on the parting plane).        They are able to have cooling holes/bores (for a specific mass flow of cooling air).        They should absorb large axial and radial forces.        They should have a large axial and radial movement clearance, especially during transient operations.        They should be resistant to temperature (fatigue strength-creep strength).        They should be simply and inexpensively producible.        They must not rotate in the circumferential direction during operation—this necessitates the installing of circumferential locking means.        
The sealing segments are to be installed before inserting the outer shells 23 into the flange 28 which is provided for it, but they could also first be installed in the gas turbine. The sealing segments can have a circumferential locking means. For the circumferential locking means, for example a groove is provided and a locking pin, having already been welded in, is located in the flange 28 of the outer shell 23.
The sealing segments can furthermore have a groove or a slot for narrow seals (knife-edge seals) in the side faces (“wedge faces”). During installation, these seals also have to be inserted. The inserting of the seals into the grooves, and additionally the inserting of the sealing segments into the flange which is provided for them, can prove to be exceptionally awkward and is directly dependent upon the geometric design of the sealing-segment foot (pos. 44 in FIG. 4), and also upon the design of the outer-shell flange 28. The outer shells 23, which are thermally very severely stressed, move transiently axially and radially; in doing so, high compressive and tensile stresses ensue.
The sealing segment forms the (mechanical) linking element from the combustor 15, to the turbine vane carrier 47, which element moves transiently in a predominantly axial manner. The operating period which is required by the outer shell 23 is typically two so-called service intervals (“service intervals/service cycles”). An operating interval describes the time between the (re-)commissioning of the combustor and the reconditioning of the components.